I think that the no riverboard rule on Grand Canyon only applies to Carlson riverboards, I think it might because I looked up riverboards and found out the Carlson riverboard is in fact a rescue board, and i read on their regulations is said Carlson riverboards are for rescue purposes only. But what about anvils riverboards, and other hydrospeed riverboards that are actually used as a sport. I noticed the rule addressed and said Carlson riverboards the overgrown kick board looking things, so they might allow hydrospeed riverboards they allow paddle boards.